1. Field of the Invention
The present disclosure relates to new and improved methods and apparatus for hybrid microwave horns for transmission of information over send and receive frequencies within the Ka-band separated by a guard band. Near-HE11 modes at the horn aperture produce high power gain and low cross-polarization for signals processed within both the send and receive regions of the Ka-band.
2. Brief Description of Related Developments
The Ka-band is used, for example, for transfer of graphics, video, voice, commands, control signals and other data types between a ground station and one or more geostationary satellite. Data is transferred from a ground station over an uplink band within the Ka-band to a satellite. Similarly, data is transferred from a satellite over a downlink band within the Ka-band to the same or another ground station. A horn can be used alone or in combination with a parabolic reflector antenna, or other reflector type, to achieve additional signal gain for the various types of data transferred among earth stations and satellites.
A new, improved and non-obvious multi-segment microwave horn is disclosed. The horn is designed for operating within a first window of a selected frequency band, for example, the Ka-band, for transmitting information to a communication target. The horn also operates within a second window of a selected frequency of the selected frequency band for receiving information from a communication target. The horn includes a circular throat segment with alternating grooves and webs that have linearly increasing groove widths expanding toward the horn aperture. This segment of the horn provides wide-band impedance matching to the input. A circular middle segment includes an up-angle flare section and a down-angle flare section. Each of the two segments includes dual depth corrugations for optimizing the reception and transmission of information through the horn by generating a near-HE11 mode. The final segment of the horn includes a smooth wall conical segment having a minor circumference enclosing an area that matches the area within the circumference of the last groove and a major circumference enclosing an area that matches the area within the circumference of the last web. The area of the major circumference is the horn""s aperture. This structure allows the radius of the aperture of the horn to extend to the fullest possible limit in the absence of corrugations and thus provides the maximum possible aperture real estate area.
A new, improved and non-obvious method is also disclosed. The method steps include operating a horn within a first window of a selected frequency band, for example, the Ka-band, for transmitting information to a communication target and within a second window of the selected frequency band for receiving information from a communication target. The method steps further include creating a circular throat segment including alternating grooves and webs having linearly increasing groove widths toward the horn aperture for wide-band impedance matching among adjacent segments of the horn. In the next step, a circular middle segment is created using a dual truncated cone, or frustum, including an up-angle flare section and a down-angle flare section. Each dual depth flare section has dual depth corrugations for optimizing the reception and transmission of information through the horn by generating a near-HE11 mode.
The last segment of the horn is made by coupling a smooth-walled, double truncated conexe2x80x94also referred to as a geometric frustumxe2x80x94to the middle segment 13 of the horn. The minor circumference and area of the smooth-walled frustum is selected to mate with the circumference and area of the last groove xe2x80x9cA1xe2x80x9d within the middle segment of the horn. The major circumference and area of the smooth-walled frustum is selected to mate with the circumference and area of the last web xe2x80x9cB1xe2x80x9d within the middle segment of the horn. The smooth-walled frustum or truncated cone allows the radius of the horn aperture to extend to the fullest possible length and area, in the absence of corrugations, to create the maximum possible aperture real estate area.